There have been various reports of fighting between groups of "youths" in the Calais jungle camp.
Here is a typical one in the Guardian.

The absence of any detail about the destination of the buses caused great anxiety among the child refugees. By the fenced-off container area of the site, there were hundreds of people milling around, most of whom were very confused about what was planned.
...

That anger erupted into protests as dusk fell and large groups of teenage migrants made their way from the shipping containers into the deserted camp, carrying sticks and shouting. Some vehicles’ windows were smashed and some asylum seekers were reported to have been injured.

Here the Muslim mob attack is disguised and given a Blame Whitey spin. The brown people act bad because Whitey didn't treat them right.
The Daily Mail comes closer to the truth.

It was members of this group who tonight took part in the brawl, which started at around 6pm by a Christian place of worship that was left intact during the demolition of the Jungle.

'A fight broke out in the southern part of Calais camp between more than a hundred Eritrean and Afghan migrant children,' said a spokesman for the prefecture that covers Calais.

'The security forces intervened immediately to separate the two groups, and security was strengthened in the temporary reception centre.'
Order was restored by around 7pm, and there were not thought to have been any arrests or serious injuries.

But here the attack on the church is described only as a fight that happened to break out close to the church.
Something closer to the truth is found in the daily public security report in Calais.

On 1 November around 5 pm, following an initial incident in which a young migrant was kicked while he was praying, a group of around 60 to 70 young Afghans headed, in reprisal, towards a Catholic church, an Eritrean place of worship, to have a fight with around 100 other migrants.

A major brawl ensured, forcing the CRS (riot police) to use collective resources to disperse the combatants.